Word Problem

Question

Kyle plans to invest $6500, part at 6% simple interest and the rest at 7% simple interest. What is the most that he can invest at 6% and still be guaranteed at least $425 in interest per year?

Answer 1

.$3000 at 7% $3500 at 6%

.07(3000) + .06(3500) = 425

07x + .06(6500 -x ) = 425

.07x-.06x = .01 = 425 - 390 = 35

.01x = 35

x = 35/.01 = $3500 invested at 7%

$3000 invested at 6%

check the solutions

.06(3000) + .07(3500) = 180 + 245 =425